On Sat, 14 Oct 2023, Lino Sanfilippo wrote:
On 13.10.23 12:24, Ilpo Järvinen wrote:
On Thu, 12 Oct 2023, Lino Sanfilippo wrote:
On 12.10.23 15:10, Ilpo Järvinen wrote:
On Wed, 11 Oct 2023, Lino Sanfilippo wrote:
Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS settings in a RS485 configuration that has been passed by userspace. If RTS-on-send and RTS-after-send are both set or unset the configuration is adjusted and RTS-after-send is disabled and RTS-on-send enabled.
This however makes only sense if both RTS modes are actually supported by the driver.
With commit be2e2cb1d281 ("serial: Sanitize rs485_struct") the code does take the driver support into account but only checks if one of both RTS modes are supported. This may lead to the errorneous result of RTS-on-send being set even if only RTS-after-send is supported.
Fix this by changing the implemented logic: First clear all unsupported flags in the RS485 configuration, then adjust an invalid RTS setting by taking into account which RTS mode is supported.
Cc: stable@vger.kernel.org Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct") Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com
drivers/tty/serial/serial_core.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 697c36dc7ec8..f4feebf8200f 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1370,19 +1370,27 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 return; }
rs485->flags &= supported_flags;/* Pick sane settings if the user hasn't */
if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
if (!(rs485->flags & SER_RS485_RTS_ON_SEND) == !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
dev_warn_ratelimited(port->dev,"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",port->name, port->line);rs485->flags |= SER_RS485_RTS_ON_SEND;rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;}
if (supported_flags & SER_RS485_RTS_ON_SEND) {rs485->flags |= SER_RS485_RTS_ON_SEND;rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
rs485->flags &= supported_flags;
dev_warn_ratelimited(port->dev,"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",port->name, port->line);} else {rs485->flags |= SER_RS485_RTS_AFTER_SEND;rs485->flags &= ~SER_RS485_RTS_ON_SEND;So if neither of the flags is supported, what will happen? You might want add if after that else?
I would consider this a bug in the driver, as at least one of both modes has to be supported. If the driver does not have at least one of both flags set in rs485_supported.flags we could print a warning though. Would you prefer that?
8250_exar.c needs to fixed then?
I was taking these as things one can
"configure" even if when there's support only for a one of them there's not that much to configure. As there was neither in 8250_exar's code, I didn't add either flag.
But I suppose your interpretation of those flag makes more sense.
IMHO this is consistent with what we have in uart_get_rs485_mode(). This function ensures that we have at least one RTS mode set (with default to RTS_ON_SEND). So concerning 8250_exar.c, I think it should be fixed (havent noticed the missing RTS mode though until you mentioned it). Would you like to provide a fix for this or shall I include one into the next version of this series?
Just create that fix yourself thank you and include it into your series, I'm busy with other stuff currently.